Research on the Influence of AGC Mode Dispatching Operation on Vibration of Hydrogenerator Units REN Leming 1Qiao Xiaoming 1 Qian 1 Liu Lihua 2, Yuan Wenyang 2, Xiao Li 2 (1. Tien Shui Tan Hydropower Plant, Lishui 323000, Zhejiang; 2 School of Civil Engineering, Wuhan University, Hubei Wuhan 430072) The vibration of the component is strengthened by the hydraulic vibration zone. The pressure of the draft tube fluctuates greatly, and the components of the unit generate cyclic alternating stress to cause fatigue damage. From the production point of view, the basic methods for re-determining the peak starting point of the unit and the anti-fatigue strength of the working parts of the high unit are proposed. These methods are simple and scientific and have good practical value. There are not many studies on the law, size and route, and no detailed research results have been seen. In this paper, combined with the vibration example of Unit 4 of Jinshuitan Hydropower Station, the field test and operation summary are carried out, and the mechanism of the influence of AGC operation on the hydropower unit is basically mastered. 1Basic situation The basic parameters of No. 4 hydro-generators in Jinshuitan Power Station are as shown in Table 1. With the development of China's electric power industry, in recent years, the main thermal power plants and hydropower units have been put into operation in automatic power generation control (AGC) mode. While technical and management meet the needs of the power grid, the AGC mode dispatching operation also brings a series of problems to the hydraulic unit, such as increased vibration of the unit, easy damage and looseness of the turbine components, and changes in the opening of the water guide vane. It has a negative impact on the operation of the unit and shortens the service life of the unit. Current regulations on the influence of AGC mode dispatching operation on the unit 1 The basic parameters of the hydraulic turbine generator of the tight water beach power station The rated output of the turbine generator / kW model 640 rated speed / min. 1 maximum head / m rated speed / r. min * Rated voltage / kV runaway speed /.min1 minimum head / m runaway speed / r ° min power factor rotor weight / t design head / m suction height / m must determine output / kW thrust load / t guarantee efficiency / % rated current /A manufacturer Hangzhou Power Generation Equipment Factory manufacturer Hangzhou Power Generation Equipment Factory 09m, downstream water level 19m. Turbine maximum efficiency 92.5%, suction height 2.5m, draft tube Zb type, turbine with WT-S-100 type electro-hydraulic speed regulation And YS-2.5 hydraulic device. The installation height of the turbine is 99.6 m, and the Hs=*2.88m device cavitation coefficient of the downstream water level of the corresponding machine is 0.185. The runner adopts 0Cr13Ni4CuMo stainless steel blades. The rated voltage of the generator is 10.5kV, CD2=4X107N-m2, the phase modulation and phase-input capacity are 40,000 kVar, and it is equipped with a thyristor excitation device. 2 Operation Summary Six hydroelectric generators of the power plant were put into operation in the AGC mode of the volute pulsation pressure since October 1997. During operation, it was found that the dispatching center often kept the unit in a rotating standby state for the convenience of load regulation, that is, the unit was running at no load; the load was adjusted frequently. From the statistics of the power generation operation of the unit from 1995 to 1999 (Table 2), after the AGC mode dispatch operation of the unit is put into operation, the power generation per unit operation hour is significantly reduced, indicating that the unit load time with local load increases; the average number of start and stop times of the unit is large. increase. For example, in 1998, the total power generation of power plants was basically the same as that of 1995, but its unit hourly power generation was 21% less, while the average number of single-machine starts and stops reached 856.2 times, 49% more than in 1995. The most recent statistics show that : The unit will run from no-load operation to partial load operation in less than 1h, and it will go back and forth up to 6 times. Table 2 Jishuitan Hydropower Station Units 1995-1999 Power Generation Operation Statistics Year Total Power Generation kWhhh Total Operation Hours/h Single Machine Hours Power Generation Million kW°h Unit Total Starts and Stops Number Single Machine Average Start and Stop Times Note: 1 Total installed capacity of power plants The AGC investment time of the 6X50MW.2 power plant unit was October 1997. 3 In 1996, the basin was a dry year, and generating electricity in the unit was an abnormal situation. After the unit is put into the AGC mode for a period of time, its operating condition is relatively poor. The reaction is that the steering shaft swing is too large, the vibration displacement of the load-bearing frame and the top cover is increased, and the draft tube, the large shaft center and the top cover are too frequent. Impact on the rotating parts of the turbine and the water guiding mechanism: On April 4, 12000, when the unit No. 1 was in operation, the metal impact sound was heard from the top cover, and the machine was immediately shut down for inspection. It was found that the top cover decompression plate and the runner crowned the water. The boards have been damaged, and they have to be temporarily overhauled. The runners and top covers are returned to the manufacturer for repair, and the water deflectors and pressure reducing plates are remanufactured and installed, causing great economic losses. 2 In the past 2 years, the unit has continuously appeared that the double-arm back cover of the guide vane transmission mechanism is loose, the shear pin is cut off when the machine is turned off, and the guide vane cannot be fully closed. In the overhaul of the unit, it was also found that the wear of the piston ring and the double arm pin of the servomotor was significantly larger than before. The leakage of water around the inlet tube of the 3 unit is obviously increased. 3 Field tests The parameters that characterize the operational stability of the turbine are vibration, swing and pressure pulsation. Among them, vibration is the main factor affecting the stability of the unit operation, and water pressure pulsation is the main cause of vibration. 3.1 Test conditions *n is the bli law of the influence of *AGC mode on the vibration of the unit. The test conditions are divided into three types: 1 smooth operation, that is, the unit runs smoothly under a constant load; 2 non-stationary operation The central control room personnel operate the unit to change operation within a certain load range; 3AGC operation, the unit is integrated into the power grid and dispatched by the dispatch center. 3.2 Test method Taking into account the characteristics of the unit vibration and highlighting the research theme, the test adopts the electric test method for detection. The three sensors of swing, displacement and water pressure are arranged in the test. The vibration signal is automatically sampled by the data collector, and the sampling frequency is 1 Hz. According to the calibration record, the collected signals are converted to obtain various vibration and pulsation values ​​of the unit. Referring to the relevant 121, the unit measurement point arrangement and test block diagram are as shown. In order to facilitate the study of the basic laws of unit vibration, some of the data of the test are classified into Table 3, and the test result data is further converted into and. 4 Test results analysis From Table 3 and it can be seen that the unit has two vibration zones when the constant load is running smoothly, and 15 ~ 25MW is the relatively strong vibration zone of the unit (main frequency Hz). The area is large, the vibration intensity is high, and the tail water flow state Not good, the water pressure pulsation is large (8.95 ~ 34.03m), the unit should not work for a long time. Adjust the load within this range, the vertical vibration displacement of the top cover (the guide vane opening degree is 64%, the main frequency 0.97 water pipe and the top cover will also generate negative pressure, but the pressure fluctuation intensity and the unit vibration amount are not large, this negative pressure ( A 0. In order to improve the working efficiency of the turbine, the unit can operate in this area. The steering angle of the unit, the vibration displacement of the frame and the top cover, and the working pulsation pressure of the turbine are all stable in the ~50MW load range. It is the better working condition of the unit vibration, and its swing and vibration displacement are 15% less than the strong vibration area. ~60%. It shows that the vibration peak caused by the unit load change is generated in the vibration working area of ​​the unit (about 5MW). The unit is damaged by the AGC operation. This is mainly caused by the frequent changes of the load passing through the vibration zone of the unit. The main energy is concentrated in 0.24 non-stationary operation (0-0-45MW) top cover Z-direction vibration displacement change diagram IS IS 丨 丨 S S 表 表 表 表 表 表 表 表 表 表 表 表 表 表 表 表 表 表 表 表 表 表 表 表 表 表 表 表 表 表 表 表 表 表 表 表 表 表 表 表 表 表Upward Y to the upper frame Z to the top cover Z to the top cover water pressure tail pipe water pressure volute water pressure smooth running non-stationary operation Note: 1A represents the amplitude; 2 force means the frequency division represents the maximum amplitude of the water pressure pulsation. The vibration amount occurring during the unit load adjustment process is 5%~20% larger than the maximum vibration amount of stable operation in the same load range. For example, the load is stable at 15MW. The upper frame Z-direction maximum displacement is 87.4rtn, and the load is at When the value of 0~30MW changes, the value reaches 106, um. Compared with the displacement, the swing of the unit changes with the pressure of the water body, but compared with the vertical displacement of the top cover and the frame of the turbine. The change value is not large. It is inferred that the size of the unit swing is mainly determined by the mechanical precision of the unit installation. It has little relationship with the pulsation pressure of the volute and the draft tube. Since the unit swing is not related to the pulsation pressure of the power generation flow, it can be seen from the measured data that the AGC operation mode only has a large impact on the vertical vibration displacement of the unit. The amount of vibration caused by AGC operating load regulation is not much different from the amount of vibration caused by artificial adjustment (non-stationary operation) in the control room of the power plant. 5 Conclusions and recommendations 5.1 Conclusion ~25MW is a relatively strong vibration zone unit is not suitable for long-term work in this area. The load is adjusted within this range, and the vertical vibration displacement of the top cover is large. The 35MW local area is a sub-strong vibration zone of the unit. Due to the air-intake measures, the vibration of the unit in this area is not large. It can be considered that the 30 sets of vibrations are better than the optimal working conditions, and the swing and vibration displacement are generally small. Changes in the range of ~50MW will not cause strong vibration. The damage of the turbine components is mainly caused by the vibration of the components caused by the vibration and cyclic alternating stress caused by the unit load frequently passing through the strong vibration zone (sometimes working in the strong vibration zone). Due to the excessive movement of the unit after the operation of the AGC mode, the wear of the piston ring and the transmission component pin is increased, and the amount of oil in the front and rear chambers of the piston cylinder and the gap between the pin and the pin hole of the transmission member are added. Although the unit swing varies with the pressure of the water body, its value changes relatively little in the AGC mode of operation. The unit starts and stops frequently, and the vibration amount is intensified. It is easy to cause the loosening of the connecting nut of the component, especially the turbine connecting nut directly subjected to pressure, such as the double arm back cap. In the AGC operation mode, the pressure of the draft tube frequently fluctuates greatly, and the steel lining of the draft tube produces alternating elastic expansion and contraction, which causes the lining and the concrete to partially detach, resulting in the leakage of the machine pit. 5.2 Recommendations (1) It is recommended that the unit not be frequently opened, stable in the range of 30 ~ 50MW, and 30MW as the starting point of the peaking of the unit. (2) If the peaking of the unit needs to be frequently turned on, or work in the range of 5 ~ 25MW, it is recommended to take measures (such as Mn steel material, surface rolling treatment, etc.) to improve the fatigue resistance of the working parts of the turbine. Wang Qilun hydraulic unit vibration Beijing: Water Resources and Electric Power Press, 1986. Liu Zaihua. Foundation of Engineering Structure Breaking Design M Bu Wuhan: Huazhong University of Science and Technology Press, 1990. 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